1. Field of the Invention
The invention relates to an intervertebral implant comprising a hollow body made in one piece and having an upper wall configured to engage a first vertebral end plate, a lower wall configured to engage a second vertebral end plate, two opposite sidewalls connecting the upper wall and the lower wall, respectively, and a load transmitting part configured to transmit load between the upper wall and the lower wall. The implant can assume a compressed condition in which it has a first height and a first width and an expanded condition in which it has a second height greater than the first height. The implant is made of a material that exhibits shape memory properties such that the implant can assume the expanded condition upon heating it.
2. Description of Related Art
US 2003/0195631 A1 describes spacers made of a shape-memory material that are used to ease insertion into an intradiscal space. The known spacer that is adapted to artificial disc replacement surgery comprises a piece of shape-memory material that is flattened or otherwise compacted prior to insertion and assumes a desired biconvex shape after it is positioned.
Other intervertebral disc prostheses using properties of shape-memory metals are known. For example, US 2009/0076613 A1 describes an intervertebral disc prosthesis including a base plate, a top plate, and at least two springs arranged between the base plate and the top plate, wherein the springs each have a loop-shaped section and two ends that are connected to the base plate and the top plate, respectively. The springs may be made of a shape-memory alloy.